/*** WARNING - THIS HAS NEVER BEEN FINISHED ***/
/*****************************************************************************
* chap.c - Network Challenge Handshake Authentication Protocol program file.
*
* Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
* portions Copyright (c) 1997 by Global Election Systems Inc.
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice and the following disclaimer are included verbatim in any
* distributions. No written agreement, license, or royalty fee is required
* for any of the authorized uses.
*
* THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************
* REVISION HISTORY
*
* 03-01-01 Marc Boucher <marc@mbsi.ca>
*   Ported to lwIP.
* 97-12-04 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
*   Original based on BSD chap.c.
*****************************************************************************/
/*
 * chap.c - Challenge Handshake Authentication Protocol.
 *
 * Copyright (c) 1993 The Australian National University.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the Australian National University.  The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Copyright (c) 1991 Gregory M. Christy.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Gregory M. Christy.  The name of the author may not be used to
 * endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include "lwip/opt.h"

#if PPP_SUPPORT  /* don't build if not configured for use in lwipopts.h */

#if CHAP_SUPPORT /* don't build if not configured for use in lwipopts.h */

#include "ppp_impl.h"
#include "pppdebug.h"

#include "magic.h"
#include "randm.h"
#include "auth.h"
#include "md5.h"
#include "chap.h"
#include "chpms.h"

#include <string.h>

#if 0 /* UNUSED */
/*
 * Command-line options.
 */
static option_t chap_option_list[] = {
	{
		"chap-restart", o_int, &chap[0].timeouttime,
		"Set timeout for CHAP"
	},
	{
		"chap-max-challenge", o_int, &chap[0].max_transmits,
		"Set max #xmits for challenge"
	},
	{
		"chap-interval", o_int, &chap[0].chal_interval,
		"Set interval for rechallenge"
	},
#ifdef MSLANMAN
	{
		"ms-lanman", o_bool, &ms_lanman,
		"Use LanMan passwd when using MS-CHAP", 1
	},
#endif
	{ NULL }
};
#endif /* UNUSED */

/*
 * Protocol entry points.
 */
static void ChapInit(int);
static void ChapLowerUp(int);
static void ChapLowerDown(int);
static void ChapInput(int, u_char*, int);
static void ChapProtocolReject(int);
#if PPP_ADDITIONAL_CALLBACKS
	static int  ChapPrintPkt(u_char*, int, void (*)(void*, char*, ...), void*);
#endif

struct protent chap_protent = {
	PPP_CHAP,
	ChapInit,
	ChapInput,
	ChapProtocolReject,
	ChapLowerUp,
	ChapLowerDown,
	NULL,
	NULL,
#if PPP_ADDITIONAL_CALLBACKS
	ChapPrintPkt,
	NULL,
#endif /* PPP_ADDITIONAL_CALLBACKS */
	1,
	"CHAP",
#if PPP_ADDITIONAL_CALLBACKS
	NULL,
	NULL,
	NULL
#endif /* PPP_ADDITIONAL_CALLBACKS */
};

chap_state chap[NUM_PPP]; /* CHAP state; one for each unit */

static void ChapChallengeTimeout(void*);
static void ChapResponseTimeout(void*);
static void ChapReceiveChallenge(chap_state*, u_char*, u_char, int);
static void ChapRechallenge(void*);
static void ChapReceiveResponse(chap_state*, u_char*, int, int);
static void ChapReceiveSuccess(chap_state* cstate, u_char* inp, u_char id, int len);
static void ChapReceiveFailure(chap_state* cstate, u_char* inp, u_char id, int len);
static void ChapSendStatus(chap_state*, int);
static void ChapSendChallenge(chap_state*);
static void ChapSendResponse(chap_state*);
static void ChapGenChallenge(chap_state*);

/*
 * ChapInit - Initialize a CHAP unit.
 */
static void
ChapInit(int unit)
{
	chap_state* cstate = &chap[unit];

	BZERO(cstate, sizeof(*cstate));
	cstate->unit = unit;
	cstate->clientstate = CHAPCS_INITIAL;
	cstate->serverstate = CHAPSS_INITIAL;
	cstate->timeouttime = CHAP_DEFTIMEOUT;
	cstate->max_transmits = CHAP_DEFTRANSMITS;
	/* random number generator is initialized in magic_init */
}


/*
 * ChapAuthWithPeer - Authenticate us with our peer (start client).
 *
 */
void
ChapAuthWithPeer(int unit, char* our_name, u_char digest)
{
	chap_state* cstate = &chap[unit];

	cstate->resp_name = our_name;
	cstate->resp_type = digest;

	if(cstate->clientstate == CHAPCS_INITIAL ||
	        cstate->clientstate == CHAPCS_PENDING) {
		/* lower layer isn't up - wait until later */
		cstate->clientstate = CHAPCS_PENDING;
		return;
	}

	/*
	 * We get here as a result of LCP coming up.
	 * So even if CHAP was open before, we will
	 * have to re-authenticate ourselves.
	 */
	cstate->clientstate = CHAPCS_LISTEN;
}


/*
 * ChapAuthPeer - Authenticate our peer (start server).
 */
void
ChapAuthPeer(int unit, char* our_name, u_char digest)
{
	chap_state* cstate = &chap[unit];

	cstate->chal_name = our_name;
	cstate->chal_type = digest;

	if(cstate->serverstate == CHAPSS_INITIAL ||
	        cstate->serverstate == CHAPSS_PENDING) {
		/* lower layer isn't up - wait until later */
		cstate->serverstate = CHAPSS_PENDING;
		return;
	}

	ChapGenChallenge(cstate);
	ChapSendChallenge(cstate);    /* crank it up dude! */
	cstate->serverstate = CHAPSS_INITIAL_CHAL;
}


/*
 * ChapChallengeTimeout - Timeout expired on sending challenge.
 */
static void
ChapChallengeTimeout(void* arg)
{
	chap_state* cstate = (chap_state*) arg;

	/* if we aren't sending challenges, don't worry.  then again we */
	/* probably shouldn't be here either */
	if(cstate->serverstate != CHAPSS_INITIAL_CHAL &&
	        cstate->serverstate != CHAPSS_RECHALLENGE) {
		return;
	}

	if(cstate->chal_transmits >= cstate->max_transmits) {
		/* give up on peer */
		CHAPDEBUG(LOG_ERR, ("Peer failed to respond to CHAP challenge\n"));
		cstate->serverstate = CHAPSS_BADAUTH;
		auth_peer_fail(cstate->unit, PPP_CHAP);
		return;
	}

	ChapSendChallenge(cstate); /* Re-send challenge */
}


/*
 * ChapResponseTimeout - Timeout expired on sending response.
 */
static void
ChapResponseTimeout(void* arg)
{
	chap_state* cstate = (chap_state*) arg;

	/* if we aren't sending a response, don't worry. */
	if(cstate->clientstate != CHAPCS_RESPONSE) {
		return;
	}

	ChapSendResponse(cstate);    /* re-send response */
}


/*
 * ChapRechallenge - Time to challenge the peer again.
 */
static void
ChapRechallenge(void* arg)
{
	chap_state* cstate = (chap_state*) arg;

	/* if we aren't sending a response, don't worry. */
	if(cstate->serverstate != CHAPSS_OPEN) {
		return;
	}

	ChapGenChallenge(cstate);
	ChapSendChallenge(cstate);
	cstate->serverstate = CHAPSS_RECHALLENGE;
}


/*
 * ChapLowerUp - The lower layer is up.
 *
 * Start up if we have pending requests.
 */
static void
ChapLowerUp(int unit)
{
	chap_state* cstate = &chap[unit];

	if(cstate->clientstate == CHAPCS_INITIAL) {
		cstate->clientstate = CHAPCS_CLOSED;
	} else if(cstate->clientstate == CHAPCS_PENDING) {
		cstate->clientstate = CHAPCS_LISTEN;
	}

	if(cstate->serverstate == CHAPSS_INITIAL) {
		cstate->serverstate = CHAPSS_CLOSED;
	} else if(cstate->serverstate == CHAPSS_PENDING) {
		ChapGenChallenge(cstate);
		ChapSendChallenge(cstate);
		cstate->serverstate = CHAPSS_INITIAL_CHAL;
	}
}


/*
 * ChapLowerDown - The lower layer is down.
 *
 * Cancel all timeouts.
 */
static void
ChapLowerDown(int unit)
{
	chap_state* cstate = &chap[unit];

	/* Timeout(s) pending?  Cancel if so. */
	if(cstate->serverstate == CHAPSS_INITIAL_CHAL ||
	        cstate->serverstate == CHAPSS_RECHALLENGE) {
		UNTIMEOUT(ChapChallengeTimeout, cstate);
	} else if(cstate->serverstate == CHAPSS_OPEN
	          && cstate->chal_interval != 0) {
		UNTIMEOUT(ChapRechallenge, cstate);
	}

	if(cstate->clientstate == CHAPCS_RESPONSE) {
		UNTIMEOUT(ChapResponseTimeout, cstate);
	}

	cstate->clientstate = CHAPCS_INITIAL;
	cstate->serverstate = CHAPSS_INITIAL;
}


/*
 * ChapProtocolReject - Peer doesn't grok CHAP.
 */
static void
ChapProtocolReject(int unit)
{
	chap_state* cstate = &chap[unit];

	if(cstate->serverstate != CHAPSS_INITIAL &&
	        cstate->serverstate != CHAPSS_CLOSED) {
		auth_peer_fail(unit, PPP_CHAP);
	}

	if(cstate->clientstate != CHAPCS_INITIAL &&
	        cstate->clientstate != CHAPCS_CLOSED) {
		auth_withpeer_fail(unit, PPP_CHAP); /* lwip: just sets the PPP error code on this unit to PPPERR_AUTHFAIL */
	}

	ChapLowerDown(unit); /* shutdown chap */
}


/*
 * ChapInput - Input CHAP packet.
 */
static void
ChapInput(int unit, u_char* inpacket, int packet_len)
{
	chap_state* cstate = &chap[unit];
	u_char* inp;
	u_char code, id;
	int len;

	/*
	 * Parse header (code, id and length).
	 * If packet too short, drop it.
	 */
	inp = inpacket;

	if(packet_len < CHAP_HEADERLEN) {
		CHAPDEBUG(LOG_INFO, ("ChapInput: rcvd short header.\n"));
		return;
	}

	GETCHAR(code, inp);
	GETCHAR(id, inp);
	GETSHORT(len, inp);

	if(len < CHAP_HEADERLEN) {
		CHAPDEBUG(LOG_INFO, ("ChapInput: rcvd illegal length.\n"));
		return;
	}

	if(len > packet_len) {
		CHAPDEBUG(LOG_INFO, ("ChapInput: rcvd short packet.\n"));
		return;
	}

	len -= CHAP_HEADERLEN;

	/*
	 * Action depends on code (as in fact it usually does :-).
	 */
	switch(code) {
		case CHAP_CHALLENGE:
			ChapReceiveChallenge(cstate, inp, id, len);
			break;

		case CHAP_RESPONSE:
			ChapReceiveResponse(cstate, inp, id, len);
			break;

		case CHAP_FAILURE:
			ChapReceiveFailure(cstate, inp, id, len);
			break;

		case CHAP_SUCCESS:
			ChapReceiveSuccess(cstate, inp, id, len);
			break;

		default:        /* Need code reject? */
			CHAPDEBUG(LOG_WARNING, ("Unknown CHAP code (%d) received.\n", code));
			break;
	}
}


/*
 * ChapReceiveChallenge - Receive Challenge and send Response.
 */
static void
ChapReceiveChallenge(chap_state* cstate, u_char* inp, u_char id, int len)
{
	int rchallenge_len;
	u_char* rchallenge;
	int secret_len;
	char secret[MAXSECRETLEN];
	char rhostname[256];
	MD5_CTX mdContext;
	u_char hash[MD5_SIGNATURE_SIZE];

	CHAPDEBUG(LOG_INFO, ("ChapReceiveChallenge: Rcvd id %d.\n", id));

	if(cstate->clientstate == CHAPCS_CLOSED ||
	        cstate->clientstate == CHAPCS_PENDING) {
		CHAPDEBUG(LOG_INFO, ("ChapReceiveChallenge: in state %d\n",
		                     cstate->clientstate));
		return;
	}

	if(len < 2) {
		CHAPDEBUG(LOG_INFO, ("ChapReceiveChallenge: rcvd short packet.\n"));
		return;
	}

	GETCHAR(rchallenge_len, inp);
	len -= sizeof(u_char) + rchallenge_len;   /* now name field length */

	if(len < 0) {
		CHAPDEBUG(LOG_INFO, ("ChapReceiveChallenge: rcvd short packet.\n"));
		return;
	}

	rchallenge = inp;
	INCPTR(rchallenge_len, inp);

	if(len >= (int)sizeof(rhostname)) {
		len = sizeof(rhostname) - 1;
	}

	BCOPY(inp, rhostname, len);
	rhostname[len] = '\000';

	CHAPDEBUG(LOG_INFO, ("ChapReceiveChallenge: received name field '%s'\n",
	                     rhostname));

	/* Microsoft doesn't send their name back in the PPP packet */
	if(ppp_settings.remote_name[0] != 0 && (ppp_settings.explicit_remote || rhostname[0] == 0)) {
		strncpy(rhostname, ppp_settings.remote_name, sizeof(rhostname));
		rhostname[sizeof(rhostname) - 1] = 0;
		CHAPDEBUG(LOG_INFO, ("ChapReceiveChallenge: using '%s' as remote name\n",
		                     rhostname));
	}

	/* get secret for authenticating ourselves with the specified host */
	if(!get_secret(cstate->unit, cstate->resp_name, rhostname,
	               secret, &secret_len, 0)) {
		secret_len = 0;    /* assume null secret if can't find one */
		CHAPDEBUG(LOG_WARNING, ("No CHAP secret found for authenticating us to %s\n",
		                        rhostname));
	}

	/* cancel response send timeout if necessary */
	if(cstate->clientstate == CHAPCS_RESPONSE) {
		UNTIMEOUT(ChapResponseTimeout, cstate);
	}

	cstate->resp_id = id;
	cstate->resp_transmits = 0;

	/*  generate MD based on negotiated type */
	switch(cstate->resp_type) {

		case CHAP_DIGEST_MD5:
			MD5Init(&mdContext);
			MD5Update(&mdContext, &cstate->resp_id, 1);
			MD5Update(&mdContext, (u_char*)secret, secret_len);
			MD5Update(&mdContext, rchallenge, rchallenge_len);
			MD5Final(hash, &mdContext);
			BCOPY(hash, cstate->response, MD5_SIGNATURE_SIZE);
			cstate->resp_length = MD5_SIGNATURE_SIZE;
			break;

#if MSCHAP_SUPPORT

		case CHAP_MICROSOFT:
			ChapMS(cstate, rchallenge, rchallenge_len, secret, secret_len);
			break;
#endif

		default:
			CHAPDEBUG(LOG_INFO, ("unknown digest type %d\n", cstate->resp_type));
			return;
	}

	BZERO(secret, sizeof(secret));
	ChapSendResponse(cstate);
}


/*
 * ChapReceiveResponse - Receive and process response.
 */
static void
ChapReceiveResponse(chap_state* cstate, u_char* inp, int id, int len)
{
	u_char* remmd, remmd_len;
	int secret_len, old_state;
	int code;
	char rhostname[256];
	MD5_CTX mdContext;
	char secret[MAXSECRETLEN];
	u_char hash[MD5_SIGNATURE_SIZE];

	CHAPDEBUG(LOG_INFO, ("ChapReceiveResponse: Rcvd id %d.\n", id));

	if(cstate->serverstate == CHAPSS_CLOSED ||
	        cstate->serverstate == CHAPSS_PENDING) {
		CHAPDEBUG(LOG_INFO, ("ChapReceiveResponse: in state %d\n",
		                     cstate->serverstate));
		return;
	}

	if(id != cstate->chal_id) {
		return;      /* doesn't match ID of last challenge */
	}

	/*
	* If we have received a duplicate or bogus Response,
	* we have to send the same answer (Success/Failure)
	* as we did for the first Response we saw.
	*/
	if(cstate->serverstate == CHAPSS_OPEN) {
		ChapSendStatus(cstate, CHAP_SUCCESS);
		return;
	}

	if(cstate->serverstate == CHAPSS_BADAUTH) {
		ChapSendStatus(cstate, CHAP_FAILURE);
		return;
	}

	if(len < 2) {
		CHAPDEBUG(LOG_INFO, ("ChapReceiveResponse: rcvd short packet.\n"));
		return;
	}

	GETCHAR(remmd_len, inp); /* get length of MD */
	remmd = inp;             /* get pointer to MD */
	INCPTR(remmd_len, inp);

	len -= sizeof(u_char) + remmd_len;

	if(len < 0) {
		CHAPDEBUG(LOG_INFO, ("ChapReceiveResponse: rcvd short packet.\n"));
		return;
	}

	UNTIMEOUT(ChapChallengeTimeout, cstate);

	if(len >= (int)sizeof(rhostname)) {
		len = sizeof(rhostname) - 1;
	}

	BCOPY(inp, rhostname, len);
	rhostname[len] = '\000';

	CHAPDEBUG(LOG_INFO, ("ChapReceiveResponse: received name field: %s\n",
	                     rhostname));

	/*
	* Get secret for authenticating them with us,
	* do the hash ourselves, and compare the result.
	*/
	code = CHAP_FAILURE;

	if(!get_secret(cstate->unit, rhostname, cstate->chal_name,
	               secret, &secret_len, 1)) {
		CHAPDEBUG(LOG_WARNING, ("No CHAP secret found for authenticating %s\n",
		                        rhostname));
	} else {
		/*  generate MD based on negotiated type */
		switch(cstate->chal_type) {

			case CHAP_DIGEST_MD5:    /* only MD5 is defined for now */
				if(remmd_len != MD5_SIGNATURE_SIZE) {
					break;      /* it's not even the right length */
				}

				MD5Init(&mdContext);
				MD5Update(&mdContext, &cstate->chal_id, 1);
				MD5Update(&mdContext, (u_char*)secret, secret_len);
				MD5Update(&mdContext, cstate->challenge, cstate->chal_len);
				MD5Final(hash, &mdContext);

				/* compare local and remote MDs and send the appropriate status */
				if(memcmp(hash, remmd, MD5_SIGNATURE_SIZE) == 0) {
					code = CHAP_SUCCESS;  /* they are the same! */
				}

				break;

			default:
				CHAPDEBUG(LOG_INFO, ("unknown digest type %d\n", cstate->chal_type));
		}
	}

	BZERO(secret, sizeof(secret));
	ChapSendStatus(cstate, code);

	if(code == CHAP_SUCCESS) {
		old_state = cstate->serverstate;
		cstate->serverstate = CHAPSS_OPEN;

		if(old_state == CHAPSS_INITIAL_CHAL) {
			auth_peer_success(cstate->unit, PPP_CHAP, rhostname, len);
		}

		if(cstate->chal_interval != 0) {
			TIMEOUT(ChapRechallenge, cstate, cstate->chal_interval);
		}
	} else {
		CHAPDEBUG(LOG_ERR, ("CHAP peer authentication failed\n"));
		cstate->serverstate = CHAPSS_BADAUTH;
		auth_peer_fail(cstate->unit, PPP_CHAP);
	}
}

/*
 * ChapReceiveSuccess - Receive Success
 */
static void
ChapReceiveSuccess(chap_state* cstate, u_char* inp, u_char id, int len)
{
	LWIP_UNUSED_ARG(id);
	LWIP_UNUSED_ARG(inp);

	CHAPDEBUG(LOG_INFO, ("ChapReceiveSuccess: Rcvd id %d.\n", id));

	if(cstate->clientstate == CHAPCS_OPEN) {
		/* presumably an answer to a duplicate response */
		return;
	}

	if(cstate->clientstate != CHAPCS_RESPONSE) {
		/* don't know what this is */
		CHAPDEBUG(LOG_INFO, ("ChapReceiveSuccess: in state %d\n",
		                     cstate->clientstate));
		return;
	}

	UNTIMEOUT(ChapResponseTimeout, cstate);

	/*
	 * Print message.
	 */
	if(len > 0) {
		PRINTMSG(inp, len);
	}

	cstate->clientstate = CHAPCS_OPEN;

	auth_withpeer_success(cstate->unit, PPP_CHAP);
}


/*
 * ChapReceiveFailure - Receive failure.
 */
static void
ChapReceiveFailure(chap_state* cstate, u_char* inp, u_char id, int len)
{
	LWIP_UNUSED_ARG(id);
	LWIP_UNUSED_ARG(inp);

	CHAPDEBUG(LOG_INFO, ("ChapReceiveFailure: Rcvd id %d.\n", id));

	if(cstate->clientstate != CHAPCS_RESPONSE) {
		/* don't know what this is */
		CHAPDEBUG(LOG_INFO, ("ChapReceiveFailure: in state %d\n",
		                     cstate->clientstate));
		return;
	}

	UNTIMEOUT(ChapResponseTimeout, cstate);

	/*
	 * Print message.
	 */
	if(len > 0) {
		PRINTMSG(inp, len);
	}

	CHAPDEBUG(LOG_ERR, ("CHAP authentication failed\n"));
	auth_withpeer_fail(cstate->unit, PPP_CHAP); /* lwip: just sets the PPP error code on this unit to PPPERR_AUTHFAIL */
}


/*
 * ChapSendChallenge - Send an Authenticate challenge.
 */
static void
ChapSendChallenge(chap_state* cstate)
{
	u_char* outp;
	int chal_len, name_len;
	int outlen;

	chal_len = cstate->chal_len;
	name_len = (int)strlen(cstate->chal_name);
	outlen = CHAP_HEADERLEN + sizeof(u_char) + chal_len + name_len;
	outp = outpacket_buf[cstate->unit];

	MAKEHEADER(outp, PPP_CHAP);    /* paste in a CHAP header */

	PUTCHAR(CHAP_CHALLENGE, outp);
	PUTCHAR(cstate->chal_id, outp);
	PUTSHORT(outlen, outp);

	PUTCHAR(chal_len, outp);    /* put length of challenge */
	BCOPY(cstate->challenge, outp, chal_len);
	INCPTR(chal_len, outp);

	BCOPY(cstate->chal_name, outp, name_len);  /* append hostname */

	pppWrite(cstate->unit, outpacket_buf[cstate->unit], outlen + PPP_HDRLEN);

	CHAPDEBUG(LOG_INFO, ("ChapSendChallenge: Sent id %d.\n", cstate->chal_id));

	TIMEOUT(ChapChallengeTimeout, cstate, cstate->timeouttime);
	++cstate->chal_transmits;
}


/*
 * ChapSendStatus - Send a status response (ack or nak).
 */
static void
ChapSendStatus(chap_state* cstate, int code)
{
	u_char* outp;
	int outlen, msglen;
	char msg[256]; /* @todo: this can be a char*, no strcpy needed */

	if(code == CHAP_SUCCESS) {
		strcpy(msg, "Welcome!");
	} else {
		strcpy(msg, "I don't like you.  Go 'way.");
	}

	msglen = (int)strlen(msg);

	outlen = CHAP_HEADERLEN + msglen;
	outp = outpacket_buf[cstate->unit];

	MAKEHEADER(outp, PPP_CHAP);    /* paste in a header */

	PUTCHAR(code, outp);
	PUTCHAR(cstate->chal_id, outp);
	PUTSHORT(outlen, outp);
	BCOPY(msg, outp, msglen);
	pppWrite(cstate->unit, outpacket_buf[cstate->unit], outlen + PPP_HDRLEN);

	CHAPDEBUG(LOG_INFO, ("ChapSendStatus: Sent code %d, id %d.\n", code,
	                     cstate->chal_id));
}

/*
 * ChapGenChallenge is used to generate a pseudo-random challenge string of
 * a pseudo-random length between min_len and max_len.  The challenge
 * string and its length are stored in *cstate, and various other fields of
 * *cstate are initialized.
 */

static void
ChapGenChallenge(chap_state* cstate)
{
	int chal_len;
	u_char* ptr = cstate->challenge;
	int i;

	/* pick a random challenge length between MIN_CHALLENGE_LENGTH and
	   MAX_CHALLENGE_LENGTH */
	chal_len = (unsigned)
	           ((((magic() >> 16) *
	              (MAX_CHALLENGE_LENGTH - MIN_CHALLENGE_LENGTH)) >> 16)
	            + MIN_CHALLENGE_LENGTH);
	LWIP_ASSERT("chal_len <= 0xff", chal_len <= 0xffff);
	cstate->chal_len = (u_char)chal_len;
	cstate->chal_id = ++cstate->id;
	cstate->chal_transmits = 0;

	/* generate a random string */
	for(i = 0; i < chal_len; i++) {
		*ptr++ = (char)(magic() & 0xff);
	}
}

/*
 * ChapSendResponse - send a response packet with values as specified
 * in *cstate.
 */
/* ARGSUSED */
static void
ChapSendResponse(chap_state* cstate)
{
	u_char* outp;
	int outlen, md_len, name_len;

	md_len = cstate->resp_length;
	name_len = (int)strlen(cstate->resp_name);
	outlen = CHAP_HEADERLEN + sizeof(u_char) + md_len + name_len;
	outp = outpacket_buf[cstate->unit];

	MAKEHEADER(outp, PPP_CHAP);

	PUTCHAR(CHAP_RESPONSE, outp);  /* we are a response */
	PUTCHAR(cstate->resp_id, outp);  /* copy id from challenge packet */
	PUTSHORT(outlen, outp);      /* packet length */

	PUTCHAR(md_len, outp);      /* length of MD */
	BCOPY(cstate->response, outp, md_len);    /* copy MD to buffer */
	INCPTR(md_len, outp);

	BCOPY(cstate->resp_name, outp, name_len);  /* append our name */

	/* send the packet */
	pppWrite(cstate->unit, outpacket_buf[cstate->unit], outlen + PPP_HDRLEN);

	cstate->clientstate = CHAPCS_RESPONSE;
	TIMEOUT(ChapResponseTimeout, cstate, cstate->timeouttime);
	++cstate->resp_transmits;
}

#if PPP_ADDITIONAL_CALLBACKS
static char* ChapCodenames[] = {
	"Challenge", "Response", "Success", "Failure"
};
/*
 * ChapPrintPkt - print the contents of a CHAP packet.
 */
static int
ChapPrintPkt(u_char* p, int plen, void (*printer)(void*, char*, ...), void* arg)
{
	int code, id, len;
	int clen, nlen;
	u_char x;

	if(plen < CHAP_HEADERLEN) {
		return 0;
	}

	GETCHAR(code, p);
	GETCHAR(id, p);
	GETSHORT(len, p);

	if(len < CHAP_HEADERLEN || len > plen) {
		return 0;
	}

	if(code >= 1 && code <= sizeof(ChapCodenames) / sizeof(char*)) {
		printer(arg, " %s", ChapCodenames[code - 1]);
	} else {
		printer(arg, " code=0x%x", code);
	}

	printer(arg, " id=0x%x", id);
	len -= CHAP_HEADERLEN;

	switch(code) {
		case CHAP_CHALLENGE:
		case CHAP_RESPONSE:
			if(len < 1) {
				break;
			}

			clen = p[0];

			if(len < clen + 1) {
				break;
			}

			++p;
			nlen = len - clen - 1;
			printer(arg, " <");

			for(; clen > 0; --clen) {
				GETCHAR(x, p);
				printer(arg, "%.2x", x);
			}

			printer(arg, ">, name = %.*Z", nlen, p);
			break;

		case CHAP_FAILURE:
		case CHAP_SUCCESS:
			printer(arg, " %.*Z", len, p);
			break;

		default:
			for(clen = len; clen > 0; --clen) {
				GETCHAR(x, p);
				printer(arg, " %.2x", x);
			}
	}

	return len + CHAP_HEADERLEN;
}
#endif /* PPP_ADDITIONAL_CALLBACKS */

#endif /* CHAP_SUPPORT */

#endif /* PPP_SUPPORT */
